Denis Defreyne
[dəˈni] • pronouns: he/him
hello@denisdefreyne.com
+49 1573 1969 173
https://denisdefreyne.com
Berlin, Germany
Denis is a competent senior/staff backend engineer with the experience of solving complex technical challenges found in large-scale, highly-available systems.
Work experience
Senior software engineer
Getsafe
Aug 2024 – Jul 2025
- Increased platform reliability and reduced customer-facing bugs by 70%.
- Improved the monitoring/observability setup and evolved the incident-response process
Staff software engineer
DG
Aug 2022 – Apr 2024
- Decreased time to release by up to 50× though adoption of state-of-the-art software delivery practices (CI/CD)
- Reduced developer setup overhead from 1 day to 10 minutes through automated tooling
- Architected and built a powerful cross-project access management solution
- Eliminated critical knowledge loss by setting up a central repository for department-wide engineering documentation
Senior software engineer
Shopify
Jul 2021 – Jun 2022
- Built a recommender system for suggested products
- Converted a legacy PHP platform into a Ruby on Rails one
Senior full-stack software engineer
BCG Digital Ventures
Jul 2019 – Jan 2021
- De-risked a legacy system (JavaScript and jQuery) by moving it onto a modern frontend stack (React and TypeScript), boosting development speed and quality
- Defined the technical direction for the internal tools team, striking a balance between business needs and long-term maintenance
- Brought consistency to the design system, and improved accessibility
Senior full-stack software engineer
Movinga
Nov 2017 – Jun 2019
- Cut infrastructure operating costs by 40–50% and brought consistency to the company’s AWS infrastructure using Terraform and Ansible
- Introduced monitoring and alerting using Prometheus and Grafana
- Tightened security of applications, services, processes, and infrastructure
Software engineer, full stack
SoundCloud
Jun 2013 – Nov 2017
- Built core parts of the monetization program (in Ruby, Rails, Scala), including a flexible logic engine to handle frequently-changing business needs
- Ran workshops around incident response
- Set up a central repository for organization-wide technical documentation
- Improved and expanded the customer support’s tooling and processes
Software developer
(various)
…–2013
- At MediaGeniX NG, expanded the broadcasting solution for MTV, Comedy Central and Nickelodeon for divisions in Europe and Southeast Asia
- At Cyan Worlds, modernized several web sites, improved SEO, set up translation workflows across seven languages
- At Netlog, optimized an abuse-detection system for social networks
- At dotProjects, developed a web-based machine translation system for large documents
Education
Master of Science in Computer Science Engineering
Ghent University
2005–2010, Ghent (Belgium)
Dissertation: Design of a recommendation system for offering services on social-network sites
Nanoc
A powerful static-site generator (1 million downloads) used at GitHub, GitLab, Prometheus, FOSDEM, and Disney.
Public speaking
A language built with third-party code reuse in mind (2023), An introduction to fibers (2019), Code as data (2018), How to memoize (2018), Let’s write a parser (2016), etc.
Technical writing
Using a modal lexer for parsing sublanguages (2022), The intricacies of implementing memoization in Ruby (2024), The complete guide to implementing equality in Ruby (2022), Using Lenses to build complex React forms in a type-safe way (2020), etc.
Co-founder. A privacy-first contact-sharing solution for Berlin nightclubs, endorsed by the Berlin Clubcommission.
Open-source projects
Cri, ddenv, ddmemoize, ddmetrics, etc (combined > 20 million downloads)
Mentoring
Mentored a diverse group of people as part of CoderDojo, RailsGirls, and multiple SoundCloud internship programs.
Core skills
Programming/markup languages
expert: Ruby, HTML, CSS
proficient: JavaScript, TypeScript, Go (Golang), Swift, Lua
Technologies
proficient: React, Ruby on Rails, AWS, PostgreSQL, MySQL, Terraform
Docker, Git, GitHub, GitLab
Processes
Scrum, Agile, continuous integration (CI), continuous delivery (CD), DevOps, test-driven development (TDD)
Natural languages
Fluent in English and Dutch.
Other interests
Programming language design, interpreter/compiler development, fiction writing, screenwriting, game design/development, acting